Cardiac resuscitator

ABSTRACT

A resuscitator apparatus includes means for detecting and counting the heart beat of a suspected heart attack victim, and means for substantially immediately applying a pacing pulse or a defibrillating pulse, as required. Thus, if the patient&#39;&#39;s pulse rate is extremely low or nonexistent, a pacing pulse is automatically applied for stimulating a heart beat in time with such pulse. However, if the electrocardiac signal from the patient indicates an extremely high rate indicative of ventricular fibrillation, a defibrillating pulse is applied to the patient. If a normal beat occurs, appropriate indication is given, and no corrective action is taken. The apparatus attaches to the patient for administering the correct electrical stimulation to the patient as soon as possible after the occurrence of the suspected attack.

United States Patent [1 1 3,703,900 Holznagel [4 Nov. 28, 1972 [54]CARDIAC RESUSCITATOR 3,384,075 5/1968 Mitchell ..128/2.06 F [72]Inventor: Melvin A. l-lolnmgel, Sherwood, FOREIGN PATENTS 0RAPPLICATIONS Ore g a 274,612 7/1951 Switzerland ..l28/2.06 E [73]Assxgnee: Cardiac Resuscitator Corporation,

Portland. g- Primary Examiner-William E. Kamm [22] Filed: 2, 1969Anomey-Buckhom, Blore, Klarquist and Sparkman [21] Appl. No.: 881,470[57] ABSTRACT [52] US. Cl. ..128/419 1, 128/2.06 F, 128/419 D [51] Int.Cl. ..A61n 1/36 [58] Field of Search ..128/2.05 T, 2.06 A, 2.06 B,128/2.06 E, 2.06 F, 2.06 G, 2.06 R, 2.06 V, 2.1 E, 419 D, 419 P, DIG. 4,421, 422

[56] References Cited UNITED STATES PATENTS 3,460,542 8/1969 Gemmer128/419 P 3,236,239 2/1966 Berkovits ..128/419 P 3,547,108 12/1970Seiffert ..128/419 D 3,174,478 3/ 1965 Kahn ..128/2.06 F 3,520,2957/1970 Kelly ..l28/2.06 R 3,144,019 8/1964 Haber ..128/2.06 A 3,510,7655/1970 Baessler ..128/206 A A resuscitator apparatus includes means fordetecting and counting the heart beat of a suspected heart attackvictim, and means for substantially immediately applying a pacing pulseor a defibrillating pulse, as required. Thus, if the patients pulse rateis extremely low or nonexistent, a pacing pulse is automatically appliedfor stimulating a heart beat in time with such pulse. However, if theelectrocardiac signal from the patient indicates an extremely high rateindicative of ventricular fibrillation, a defibrillating pulse isapplied to the patient. If a normal beat occurs, appropriate indicationis given, and no corrective action is taken. The apparatus attaches tothe patient for administering the correct electrical stimulation to thepatient as soon as possible after the occurrence of the suspectedattack.

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MELVIN A. HOLZNAGEL INVENTOR BUCKHORN, BLORE, KLARQUIST & SPARKMANATTORNEYS PMENTED um 28 I972 SHEET 2 [IF 7 K3 FIIL 4M 7 m EOPUMCDO 13mmMELVIN A.HOLZNAGEL INVENTOR BY BUCKHORN, BLORE, KLARQUIST a. SPARKMANATTORNEYS PATENTED 3, 703, 900

sum 3 or 7 FIG. 4

MELVIN A. HOLZNAGEL INVENTOR BUCKHORN, BLORE, KLARQUIST & SPARKMANATTORNEYS PATENTED 28 I97? 3. 703.;900

- sum u or 7 VEN TOR BBY BUCKHORN, BLORE, KLARQUIST 8. SPARKMANATTORNEYS MELVIN A. HfP LZNAGEL PATENTEDnuvze I972 SHEET 5 0F 7 m VI 0 Bin VI 0 m4. 4U XUOJU MELVIN A. HOLZNAG'EL INVENTOR BUCKHORN, BLORE,KLARQUIST & SPARKMAN ATTORNEYS w oE PATENTEDnnvea 1972 SHEET. 6 BF 7rLBOI MHH @ INPUT OUTPUT OUTPUT @Q OUTPUT OUTPUT i L F- OUTPUT MELVIN A.HOLZNAGEL INVENTOR TIME QOUTPUT BUCKHORN, BLORE, KLARQUIST 8. SPARKMANATTORNEYS PATENTEDHHHB I972 SHEET 7 OF 7 703 9 0 MELVIN A. HOLZNAGELINVENTOR BUCKHORN, BLORE, KLARQUIST & SPARKMAN ATTORNEYS CARDIACRESUSCITATOR BACKGROUND OF THE INVENTION An unusually large number ofheart attack victims die each year as a resultof delays in providing theintensive care required. A suspected heart attack victim typically mustbe hospitalized before receiving adequate medical attention. However, agreat many patients suffering from a coronary attack never reach thehospital. Cardiac arrests and arrhythmias such as ventricularfibrillation frequently develop within a short time after the onset ofthe attack, e.g. within the first hour, with fatal results unlessremedial steps are taken within minutes. Unless a normal rhythm can .berestored to a heart in ventricular fibrillation within minutes, seriousbrain damage or death will result.

SUMMARY OF THE INVENTION In accordance with the present invention, acardiac resuscitator is provided which is compact enough for attachmentto a suspected heart attack victim at nearly any location, and which maybe operated by comparatively unskilled personnel. The resuscitator maybe carried in an ambulance, for example, or may be conveniently storedin an industrial plant, ofiice building, hotel, or the like, forimmediate application to the suspected victim of a heart attack. Theresuscitator electrode current applicator is applied to the patient, andthe apparatus measures the electrocardiac signal from the patientsheart. If a normal heart beat is detected, an appropriate indication isgiven. However, if the heart beat is excessively slow or nonexistentindicating substantial cardiac arrest, a pacing pulse is applied to thepatient for restoring a normal heart beat. If the electrocardiac signalis very high in frequency, indicative of ventricular fibrillation orventricular tachycardia, an appropriate defibrillating impulse isapplied to the patient. The apparatus may remain applied to the patientfor detecting possible arrhythmias occurring after the onset of apossible heart attack until adequate hospitalization can be provided.

It is an object of the present invention to provide an improved cardiacresuscitator apparatus which may be applied to a suspected heart attackvictim in nearly any location prior to hospitalization.

It is a further object of the present invention to'provide an improvedcardiac resuscitator apparatus for detecting arrhythmias and providingappropriate corrective action in the absence ofa physician.

It is a further object of the present invention to provide an improvedcardiac resuscitator apparatus which is substantially portable innature.

It is a further object of the present invention'to provide an improvedcardiac resuscitator apparatus which accurately interprets theelectrocardiac signal from a suspected heart attack victim and applies acorrective impulse in cases of then determined arrhythmias.

It is a further object of the present invention to provide an improvedcardiac resuscitator apparatus which is substantially fool-proof inoperation.

The subject matter which I regard as my invention is particularlypointed out and distinctly claimed in the concluding portion of thisspecification. The invention, however, both as to organization andmethod of operation, together with further advantages and objectsthereof, may best be understood by reference to the 7 heart;

following description taken in connection with the accompanying drawingswherein like reference characters refer to like elements.

DRAWINGS FIG. 1 is a perspective view of cardiac resuscitator apparatusaccording to the present invention, shown applied to a patient;

FIG. 1a is a side view of an electrode current applicator portion of thepresent resuscitator apparatus;

FIG. 2 illustrates a typical electrocardiogram trace of the electricalsignal generated by an average healthy FIG. 3 is a block diagram ofcardiac resuscitator apparatus according to the present invention;

FIG. 4 is a schematic diagram of interface 1 portion of the apparatus asreferenced in the FIG. 3 block diagram;

FIG. 5 is a schematic diagram of the signal conditioning unit 2 portionin the block diagram;

FIG. 6 isa schematic diagram of the peak'detector 3 in the blockdiagram;

FIG. 7 is a schematic diagram of comparator 4;

FIG. 8 is a schematic diagram of counter 5;

FIG. 9 is a waveform chart illustrating typical operation of counter 5;

FIG. 10 is a schematic diagram of clock 6;

FIG. 11 is a schematic diagram of pacer 7; and

FIG. 12 is a schematic diagram of the defibrillator 8 portion of theFIG. 3 block diagram.

DETAILED-DESCRIPTION Referring to FIGS. 1 and la, illustratingresuscitator apparatus according to the present invention, the apparatusincludes a U-shaped electrode current applicator provided with a handle116 and electrodes anc@which are individually connected to the controlcabinet 112 via cable 114. The applicator is desirably formed of springplastic or plastic-covered metal electrically insulated from theelectrodes. As illustrated in the FIG. la, the applicator tends to urgecontactsQ and @toward one another so that when placed on the patient asillustrated in FIG. 1, contacts@, 2 and 3 make firm contact with thepatients body.

The electrode current applicator is placed over the left shoulder of thepatient so that electrodesand are positioned approximately above andbelow the heart, with the patient ordinarily being in a prone position.The patient is desirably strippedto the waist so that such contact maybe made with the body, or, alternatively, the applicator can be insertedbeneath clothing to some extent. Electrodeis designated the chestelectrode, with electrodecomprising the back electrode. The thirdelectrode@, termed an indifferent or neutral electrode, makes contactwith the patient in the shoulder region.

The control cabinet 1 12 contains electronic circuitry for receivingelectrocardiac signals from the aforementioned electrodes, and foranalyzing the same in order to determine whether a corrective electricalimpulse should be applied to the patient through the electrodes. Atypical cardiac signal, illustrated as an ECG trace, represents an'individual heart beat in FIG. 2. In the normal heart, the atrial portionof the heart impulse corresponds to the P wave indicated on the ECGtrace.

a 3 The impulse then stimulates the atrioventricular node and theventricles producing the QRS complex. The final portion of the trace,designated as the T wave, is

' provided by repolarization or recovery of the ventricular muscles. Thecircuitry of the present invention counts the rate of the signals of thetype illustrated in FIG. 2 produced by the individuals heart in order todetermine whether the heart rate is normal, abnormally low, orabnormally high. If the heart beat falls within normal limits, thenormal heart indicator -J, suitably comprising a pilot lamp, will light.If the heart rate is so low as to indicate substantial cardiac, arrest,a pacing pulse will be applied to the aforementioned electrodes in amanner hereinafter described. If the heart signal indicates an extremelyhigh rate, indicative of ventricular fibrillation or ventriculartachycardia, a defibrillating pulse will be applied.

In order to render the device substantially fool-proof, and topreventimproper application of electrical impulses when a proper signalcannot be received, the circuitry accordingto the present invention isprovided with continuitymeans for determining whether electrodes@,@,and@are making proper electrical connection with the patients body. Onlyafter such a determination is the heart rate indication able to bringabout the aforementioned pacing or defibrillating impulses. In additionto the inhibition of the device in the absence of proper contact withthe patients body, a poor contact indicator 1-D, suitably comprising apilot lamp, also warns the operator that proper contact with the patienthas not been established. Cabinet 1 l2 additionally includes powersupply circuitry and batteries for use in case of portable operation. Anoff-on switch as well as a pilot lamp indicating the presence of powerare suitably also included.

In operation, the electrode current applicator is applied as illustratedin FIG. 1, and the power switch is operated for energizing theapparatus. A normal heart indication may reveal the patient has merelyfainted, rather than having suffered a heart attack. However, such anindication may only indicate that arrhythrnias have not as yetdeveloped. The device is suitably left applied to the patient untiladequate medical attention is provided, and meanwhile the devicecontinuously monitors the heart during the critical period after apossible attack. For example, battery powered apparatus of the presenttype may be left attached to the patient while he is being transportedto a hospital in an ambulance.

The apparatus is relatively compact, and may be carried in an ambulance,or conveniently stored in an industrial plant, ofiice building, hotel,or the like, for immediate application to a suspected victim of a heartattack. The apparatus may be operated by comparatively unskilledpersonnel, without the need of an expert diagnosis, while awaitingconventional medical attention.

Block Diagram FIG. 3 isan electrical block diagram of the apparatusaccording to the present invention, principally located within cabinet112. Referring to FIG. 3, sensitive amplifier 1-8 in interface unit 1receives the electrocardiac signals from the patient electrodes, jointlyindicated at l-A, and applies an amplified version thereof atoconditioning unit 2 wherein the signal is which may be due to movementof the patients body. I

Also removed are portions of thenormal electrocardiac signal, as seenin- FIG. 2, known as the P and T waves, leaving only detection of theQRS complex. As

it is hereinafter indicated, disabling clamp 2-B operates to inhibittransmission of the QRS signal at times when electrical stimulation isbeing delivered to the patient.

The outputof signal conditioning unit 2 is applied to peak detector 3and comparator 4. These units comprise detection means of varyingsensitivity for detecting or developing peaks from the QRS complexrelative to previously stored values of such peaks. The detection meansfunctions over a wide range of input signal amplitude with little or nodegradation in performance. Without such a variable sensitivity feature,the system would be susceptible to noise present on large amplitudesignals, or would be unable to detect the presence of small amplitudecomplexes, or both. The apparatus also includes means for essentiallyignoring the occasional signal of unduly high amplitude, e.g. peaksassociated with ectopic beats.

Referring to the drawing, output from signal conditioning unit 2 isapplied to positive peak limiters 3-A and 3-B as well as positive peakdetectors 3-C and 3-D. The peak detectors remember and store positiveand negative peaks of the signal received, while the limiters preventstorage of a signal higher than a predetermined multiple of a previouslystored signal, e.g. twice the previously stored signal. Therefore,ectopic beats or the like do not unduly influence peak signal storage soas to interfere with nonnal circuit operation. Depending upon whetherthe positive or the negative peak stored is higher, polarity selector3-E applies an output to polarity gate 4-C causing the comparator 4 topass either positive or negative signals, according to thepredominantpolarity of the particular electrocardiac signal at hand.Thus, the maximum voltage peak developed by the heart may be eitherpositive or negative, and the circuit is effective to employ the signalvalues of the proper polarity.

Positive peak detector 3-C provides an outputto positive comparator 4-Awhile negative peak detector 3-D provides an output to negativecomparator 4-B. The comparators also receive the input signal at andsupply respective positive and negative outputs only insofar as incomingsignal peaks exceed a predetermined fraction of the previously storedpeak. Thus, in the case of high amplitude signals, the input at willhave to be large in order to produce a response mm a comparator.However, if the stored signal is smaller, a smaller input at willoperate the comparators. In this manner, the sensitivity is adjusted fordetermining peaks from the electrocardiac signal without noise which maybe associated therewith. I

The output of polarity gate 4-C is applied to oneshot multivibrator 4-D.The one-shot multivibrator produces output pulses having a width ofapproximately milliseconds to provide pulse widening. The purpose ofthis widening is to prevent two or more peaks of a QRS complex fromproducing multiple out uts at Therefore one output will be produced atfor each heart beat. The output atis also coupled to inverting gate LEfor supplying a resetting signal to the pacemaker as hereinafter morefully describe The output from the comparator is applied to counter 5,the purpose of which is to determine the heart beat rate of the patient.First, second, and third indications are produced by the counter inaccordance with whether heart beat of the patient is appreciably lowerthan normal indicating cardiac arrest, appreciably higher than normalindicating ventricular fibrillation or ventricular tachycardia, ornormal. The counter 5 includes first counter S-A receiving the signal atFirst counter 5A is a divide-by-five circuit, producing an outputapplied to flip-flop 5-B and second counter 5-D for every five inputpulses received at Second counter 5-D is also a divide-by-five counterand applies its output to flip-flop S-E for every five input pulses itreceives. Each counter is controlled by clock 6 to count for a period ofapproximately eight seconds, after which each of the counters is reset.If, during this time, counter 5-A produces an output, flipflop S-B isset. If second counter 5-D also produces an output, flip-flop 5-E isset. At the end of eight seconds, J-K flip-flops S-C and 5F are enabledby clock signal and assume conditions representative of flip-flops S-Band S-E respectively. A not-Q signal from .l-K flipflop 5-C wouldindicate counter 5-A has counted at least four pulses (counter 5Aproviding an output at the end of the fourth, ninth, fourteenth, etc.pulses). Similarly, a not-Q output from flip-flop S-F indicat s thepresence of at least twenty-five pulses at input during the eight secondperiod. Four pulses in eight seconds is equivalent to a heart rate of 30pulses per minute, and twenty-five pulses in eight seconds is equivalentto a heart rate of 187.5 pulses per minute. Thus, the presence of anot-Q output from flip-flop 5-C together with a input from flip-flop Fwill be representative of a heart beat between the aforementionedvalues. For purposes of the present discussion, these values are chosenas normal limits. Therefore, the not-Q output of flip-flop 5-C and the Qoutput of flipflop 5-F are applied to and-gate 5-l-l which operatesnormal heart indicator 5] when both its inputs are present. Indicator 5Jmay comprise a pilot lamp or the like.

Flip-flops 5-B and 5-E constitute means for remembering or storing thecount achieved during an eight second cycle by the counters. Similarly,flip-flops S-C and S-F constitute output means for remembering orstoring for a longer period the count achieved by the previousflip-flops.

It is noted that counters S-A and 5-D as well as flipflops S-B and 5Eare reset at least each eight seconds by clock 6 via signal paths andHowever, J-K fli -flops 5-C and 5-F are only cleared by a clear signalfrom or-gate 6-A in clock 6. If, at a given ,time, a not-Q output isprovided from J-K flip-flop 5-F, it indicates a count of at least 25from second counter S-D having occurred during an 8 -second interval.This not- Q output is applied to and-gate 5-K. The other input toand-gate 5-K is derived from flip-flop S-E. Thus, if during the nexteight-second interval, and-gate 5-K receives an input from flip-flop 5E,it will indicate a heart rate of over 187.5 for two successive 8 secondintervals. The circuit thereby double checks at high heart rate beforesupplying a signal to defibrillator 8. Defibrillator 8, as hereinafterdescribed, applies a single defibrillating pulse to the patientelectrodes l-A. Because of the seriousness of applying the defibrillatoroutput, a double count of the heart rate is made.

If a Q output is present at from flip-flop 5-C, a very low heart ratebelow 30 pulses per minute is present, which indicatesunduly low heartbeat or cardiac arrest. The output operates pacer 7 as hereinafterindicated for applying a periodic pacer pulse to the patient electrode1-A for stimulating a heart beat at the rate of the pacer pulse.

Clock 6 includes a clock pulse generator6-B roviding pulse outputs ateight second intervals at If a signal is present at either indicatingdefi rillator operation, or at 'ndicating faulty interface operation orinitial start conditions, the clock pulse generator 6-B is reset fromor-gate 6-A. At the same time the J-K flip-flops S-C and 5-F are clearedvia lead and a reset pulse is provided at via or-gate 6-C. Likewise,flip-flop 6-D is set. After being initially reset from or-gate 6-A,clock ulse generator 6-B starts providing clock pulses at at eightsecond intervals. At the end of each such clock pulse, a reset isprovided or-gate 6-C and flip-flop 6-D. The reset via leads and resetthe counters 5-A and 5-D as well as flipflops B and E for another cycle.At the end of such cycle, the clock pulse at causes the .l-K flip-flopsto register the condition 0 flip-flops S-B and 5-E as hereinbeforedescribed. Flip-flop 6-D provides an output at effective for enablingthe pacemaker only after a suitable period of time has elapsed forcounter 5 actually to count the heart rate. Otherwise, pacer 7 couldfalsely indicate .a low heart rate before proper counter operation.Operation of flip-flop 6-D will be further described hereinafter.

In pacer 7, pacemaker timer 7-B generates a series of timing pulses witha period of approximately 0.85 seconds, whenever the output of and-gate7-A is high. The output of and-gate 7-A is high, (1) when the circuitryhas operated at least eight seconds as indicated by a signal at@?, (2)when comparator 4 does not detect a present eart beat, and (3) whencounter 5 indicates a heart rate of below 30 beats a minute. The outputof timer 7-B triggers one-shot multivibrator 7-C which operates pacerpulse generator 7-D. The latter delivers a pacing pulse to the patientelectrodes via leads@,@, and switching diodes l-F. The switching diodesl-F essentially disconnect the pacer from the patient electrodes whenthe pacemaker produces no output. During each pacemaker pulse, output ofone-shot multivibrator 7-C operates or-gate 2-C for disabling the signalpath. If, between pacer pulses, a heart beat is detected, reset signalwill reset pacer timer 7-B via and-gate 7-A, restarting the timing ofthe 0.85 second interval. Thus, the pacer operates on a demand basis andproduces no output when spontaneous heart beats are present.

When defibrillator 8 receives an input at, oneshot multivibrator -A isset in a second state for approximately milliseconds. Output disablesthe signal path, and output resets clock 6 as well as counter 5. Thethird output of multivibrator 8-A operates defibrillator generatorthrough and-gate 8-H if input@is also present. A defibrillating pulse, ahigh energy electrical pulse, is applied through leads@ and switchingdiodes l-E, to patient electrodes l-A.

lnpuis present if the patient electrodes make proper contact andcertain. other conditions are met as hereinafter more fully described.The switching diodes essentially disconnect the defibrillator when thesame is not in use. It is observed the defibrillator operation resetsclock 6 and counter forsuccessive operations. If, after a defibrillatingpulse is applied to the patient, fibrillation or tachycardia persists,defibrillator operation will again be initiated in the same manner ashereinbefore described.

Interface 1 further includes continuity checker l-C, which determines ifthe patient electrodes are in proper electrical contact with thepatients body. If not, a poor contact indicator 1-D, suitably comprisinga pilot lamp, is energised, and defibrillator and-gate'8-B is disabledvia or-gate l-K and lead@ thus preventing defibrillator operation andpossible patient burns in case of poor electrical contact. Also in suchcase, clock 6 is reset vialead and'flip-flop 6-D is set to preventoperation of the pacer via output When the resuscitator is firststarted, start circuit l-H disables orgate l-K thereby disablingdefibrillator 8, resetting clock 6, and disabling pacer 7. Pacer 7 isoperable when flip-flop 6-D is reset from clock pulse (5-3. The outputfrom the start circuit 1-H is of short duration, and the main purposethereof is'the disabling of the pacer until the counter has time tocount.

The individual units of the resuscitator will now be considered ingreater detail.

Interface Referring to FIG. 4, illustrating interface unit 1 in greaterdetail, transistors 0101 and 0102 provide DC current sources for patientelectrodes and (2) to ground via indifferent or neutral patientelectrode@. The DC voltage at electrode@an@depends upon the resistancebetween each electrode and ground, and therefore, if eitherelectrodeoris in poor contact with the patient, a comparatively high DCvoltage will occur at that electrode. Patient electrodeis coupled to theinput and an operational amplifier U101, while the patient electrodeiscoupled to the input of an operational amplifier U102, with diodes D105,D106, D107, and D108 protecting the amplifiers during the application ofa pacing or defibrillating pulse. If the voltage at patient electrodeisless than about +0.15 volts, then the output of'U101 will be about +15volts, and the voltage at the junction of D109 and D110 will be clampedto about +5.6 volts. However, if the voltage at patient electrodeexceeds+0.15 volts, the voltage at the output of U101 will be about -15 volts,and the voltage at the junction of diodes D109 and D110 will be clampedat about 0.6 volts. The output of amplifier U102 is similarly controlledby the voltage at patient electrode@. Integrated circuit package l-K,employed as an and-gate, here comprises four nand-gates 30, 32, 34, and36 cascaded as shown. Each nand-gate has the following characteristics:If both inputs are high, the output is low. However, if either input islow, the output is high. Nand-gate 30 receives the output of bothamplifiers U101 and U102, and drives nand-gate 32,

the output of which is coupled to transistor Q103 having a poor contactindicator lamp in its collector circuit. Thus, if the output of eitheramplifier U101 or U102 drops, indicating poor patient electrode contact,lamp l-D will light.

Likewise, nand-gate 32'drives nand-gate 34 in conjunction with startcircuit l-H comprising transistor 0104. When power is first turned on,transistor Q104 is momentarily turned on. Capacitor C101 charges so thatQ104 cuts off, thereby providing a high input to nand-gate 34. Assuminggood contact is made by the patientelectrodes, and the power has beenapplied for a'short period of time, both inputs to nand-gate 34 will beup, and the output of nand-gate 36, driven by nandgate 34, will also beup. The output of nand-gate 36 is applied to leadsand Since nand-gatesare employed throughout, no inverting gate is employed in lead nor is aninverting gate required in the output of the start circuit. Bothoutputsandwill be energized so long as continuity is present to thepatients body from the patient electrodes, and so long as power has beenapplied to the apparatus'for at least a short time. Then, the clock anddefibrillator are operable.

Switching diodes 1-E and l-F, from the defibrillator andpacerrespectively, couple these units to the patient electrodes, andessentially decouple these units when neither provides an output pulse.Also, the respective diodes prevent application of a defibrillator pulseto the pacer, or a pacer pulse to the defibrillator.

Operational amplifiers U104 and U105 receive signal outputs from patientelectrodes@and@, and diodes D116 and D117, D118 and D119 limit thevoltage excursion of the inputs of these amplifiers during theoccurrence of defibrillator or pacer pulses. Each of the amplifiers U104and U105 is connected as a voltage follower, so the outputs thereof arethe same as those from patient electrodesand@respectively except the DCcomponent has been removed, and the impedance level is greatly reduced.The outputs of amplifiers U104 and U105 are applied as inputs todifferential amplifier U106 which has a voltage gain of approximately1000 as determined in part by feedback resistor R135. The output ofamplifier U106 at leadis therefore an amplified version of theelectrocardiac signal existing between patient electrode@an@except thatany DC component has been removed.

Signal Conditioning Circuit @provides an input for amplifier U201 via ahigh pass filter comprising capacitor C201 and resistor R201. Thisfilter reduces the amplitude of frequency components which lie belowabout 3 Hertz. The amplifiers feedback circuit comprising resistor R203in parallel with capacitor C202 between the output of the amplifier andits negative input, together with resistor R202 disposed between suchnegative input and ground, are arranged to inhibit amplification offrequency components above about thirty Hertz. Reverse connected diodesD201 and D202 couple the output of amplifier U201 to a high pass filtercomprising capacitor C203 and resistor R205. The reverse connecteddiodes substantially eliminate components reduced in amplitude by thepreceding filter, while the last mentioned high pass filter attenuatescomponents of the signal which lie below about 10 Hertz. Transistors0201 and Q202, having their bases connected to the junction of capacitorC203 and resistor R205 provide a low impedance output to drivesubsequent circuits, and form a second nonlinear filter. The signal attheir common emitter connection consists primarily of fast risingvoltage peaks or pulses which correspond to the fast rising portions ofthe original electrocardiac signal, i.e. the QRS complex. The commonemitter junction of transistors Q] and 0202 is connected to output leadsand Also connected to the same junction is the collector of transistorQ203 having its base driven from gate 2-C, the latter here comprising anand-gate receiving inputs and When the output of gate 2-C is low,transistor 0203 is turned off and has no effect u n the signal atHowever, if either inputor @2120 the base of transistor Q203 rises, andthe sign ati s clamped to ground. Thus, ashereinbefore descri d, thesignal path is clamped during the occurrence of either the pacing pulseor the defibrillating pulse.

Peak Detector In FIG. 6, an input on leadis coupled to peak detectors3-C and 3-D. Peak detector 3-C comprises an amplifier U301 having aparallel combination of capacitor C301 and R301 shunting its positiveinput to ground. Similarly, negative peak detector 3-D includesamplifier U302 with capacitor C301 and R302 shunting its positive inputto ground. The time constants of the C301 and R301 combination and theC302 and R302 combination are long with respect to the normal periodbetween heart beats. Therefore, capacitors C301 and C302 act as peakdetector storage capacitors and discharge only slightly between inputpulses.

Amplifiers U301 and U302 are connected as typical voltage followersexcept that diode D303 is connected between the output and the invertinginput of amplifier U301, while diode D304 is connected between theoutput and the inverting input of amplifier U302. In the case of diodeD303, for example, this diode compensates for the voltage drop whichoccurs across diode D301 w'hile capacitor C301 is charging, in order tomake the output voltage of amplifier U301 more nearly equal to the peakvalue of the positive input pulse. Amplifier U301, for example, thenprovides a low impedance source of a voltage which is representative ofthe peak value of the preceding positive voltage pulses which haveoccurred at Amplifier U302 provides a similar source of voltagerepresentative of the peak value of preceding negative voltage pulses.

The outputs of amplifiers U30] and U302 are applied to amplifiers U303and U304, respectively, each having a voltage gain of two. Thus, theoutput of each is approximately twice the stored values on theaforementioned capacitors C301 and C302. The outputs of amplifiers U301and U302 are coupled to the bases of transistors 0301 and Q302,respectively, which operate as positive and negative limiters inasmuchas their emitters are coupled to the inputs of amplifiers U301 and U302.Thus, if the input atbecomes more positive than twice the previouslystored peak value, transistor Q30l conducts, preventing an input pulseof large amplitude but short duration from charging C301 to a voltagemore positive than twice the previously stored positive peak value. Thislimiting feature prevents a single large pulse, whether originating inthe patient as in the case of an ectopic beat, or as induced into thepatient from an external source, from raising the stored peak value tosome value which is entirely unrepresentative of the average signalamplitude. Especially, the limiting feature prevents the large voltagepeaks associated with ectopic beats from decreasing the sensitivity ofthe circuit to the point where the next normal QRS complex would beundetected.

The output of U301 is attenuated by resistive dividers R317, R319 sothat approximately one-third of the stored positive peak value fromamplifier U301 is coupled to the comparator via lead Similarly, dividerR318, R320 c ples one-third the output of amplifier U302 to leadAmplifier U305 acts as a voltage comparator, and has both positive andnegative signals coupled in common to its negative input terminal. Theoutput at will be low if the magnitude of the stored positive peak valueis greater than the magnitude of the stored negative peak value, andhigh if the stored negative peak value is greater.

Comparator is more positive than the positive reference voltage at Q andnegative when the input signal is less positive than the reference. As aresult, only signals are transmitted which exceed about one-third thepreviously stored value. Without this feature, the system would besusceptible to noise present on large amplitude signals. This system isof variable sensitivity, rendering it operable with respect to cardiacsignals of different average amplitude values. The negative comparator4-B, of course, operates similarly. It is noted that the one-thirdreference values allow signal detection of a normal signal after anectopic beat, the storage of which is restricted to double amplitude.

Polarity gate 4-C comprises four nand-gates, 38, 40, 42, and 44,connected as shown. The signal from polarity selector 3-H provides oneinput for nand-gates 38 and 42, while the output of comparator 4-A isconnected to an input of nand-gate 40, and an output of comparator 4-Bis connected to an input of nand-gate 42. The output of nand-gate 44 isidentical to the output of comparator 4--A, or to the output ofcomarator 4-B, depending upon the level of the input at For example, ifthe input is high, then the signa at the output of nand-gate 44 isidentical to the signal from comparator 4-B. On the other hand, if theinput is low, the output of nand-gate 44 is identical to the signal fromcomparator 4-A. Thus the output of nand-gate 44 is either the output ofpositive comparator 4-A or the negative comparator 4-3, depending uponwhether the positive or negative peak amplitude of the electrocardiacsignal is greater as indicated by the level on lead One-shotmultivibrator 4D comprises transistors 0401 and 0402 connected in aconventional circuit and operated according to the output of polaritygate 4-C. As hereinbefore described, the one-shot multivibrator rates asa pulse extender providing an output at for about 100 milliseconds whenan input pulse occurs. This extension prevents the QRS complex of thenormal electrocardiac signal, which may comprise several peaks closelyadjacent in time, from being registered as multiple pulses. Gate 4-Ehere comprises a nand-gate providing an output for resetting the pacer.l

Counter Referring to FIG. 8, the counter comprises a first counter S-Areceiving an input from the comparator and driving a second counter 5-D.Each of these counters are divide-by-five counters providing an outputcorresponding to five input pulses. First counter 5-A supplies an outputat the end of the fourth input pulse. Its output will go high at the endof the fourth pulse and low at the end of the fifth pulse. if the inputpulse train continues, the output will go high at the end of the ninth,fourteenth, nineteenth; etc. pulses as illustrated in the waveform chartof FIG. 9, where input pulses at are indicated at the top with thecorresponding outputs of first counter 5-A immediately thereunder.

The output of first counter 5-A also drives an integrated circuitpackage connected to form flip-flop 5- B. The package includesconsecutively connected nand-gates 46, 48, 50, and 52. The first and thelast of these act as inverters. The output of nand-gate 50 is connectedto provide a circuit input for nand-gate 48, while a second input ofnand-gate 50 is provided from connection providing a reset pulse fromtheclock circuit. A momentary low input on lead resets the flip-flop sothat the output of nand-gate 50 is high. After resetting, a momentarylow level at the input of nand-gate 48, produced by momentary highlevelat the input of nand-gate 46, will cause the output of nandgate 50to go low and remain low until the flip-flop is again reset. Thus, thefourth input pulse which is applied to counter 5-A after resettingcauses the flip-flop to change to a state wherein the output ofnand-gate 50 is low, and to remain in this stateuntil the next resetpulse is applied. At the same time that the output of nand-gate 50 islow, the output of nand-gate 52 is high. These respective outputs areprovided to the J and K terminals of J-K flip-flop 5-C.

The outputs Q and not-Q of flip-flop 5-C are always in opposite states.A low input at the J terminal sets the Q output to the low level. Thestates of the Q and not-Q outputs are determined by the states of the Jand K inputs at the time of the preceding clock pulse on line J-Kflip-flops are well known to those skilled in the art. A low level atthe J input and a high level at the K input at the beginning of theclock pulse will result in a low level at the Q output, and a high levelat the not-Q output after the end of the clock pulse. The relationshipbetween the clock pulse and the setting of the J-K flip-flop s c atisillustrated in FIG. 9.

Thus, if more than four input pulses are received at after resetting offirst counter 5-A and flip-flop 5-B, but before the occurrence of aclock pulse, then the 0 output of J-K flip-flop 5-C will be low and thenot-Q output high after the end of the clock pulse. Conversely, fewerthan four input pulses at between the end of the reset pulse and thebeginning of the clock pulse will result in a high level Q output of J-Kflip-flop 5-C after the end of the clock pulse.

The circuitry comprising counter 5-D, flip-flop 5-E, and J-K flip-flop5-F operates similarly.

After the end of a clock pulse, there are three possible states whichmay exist for Qand not-Q outputs of the J-K flip-flops 5-C and 5-F. ifboth Q outputs are high, it is indicative that fewer than four countswere received duringv the previous eight second clock period, or thatthe heart beat was less than thirty beats per minute, symptomatic ofcardiac arrest. If the Q output of flip-flop 5-C is low. (and its not-Qoutput is high), and the Q output of flip-flop 5-F is high, the numberof counts received during the previous eightsecond clock period was atleast four but less than twenty-five, or a heart beat rate within thesubstantially normal range of 30 to 187.5 beats per minute. If bothnot-Q inputs are high, indicating that 25 or more countswere receivedduring the previous 8-second'clockperiod, it is indicative of a heartbeat rate of 187.5 beats per minute, or greater, symptomatic ofventricular tachycardia or ventricular fibrillation. it should be notedthat the clock period and counting ratios are parameters which mayeasily be changed. Therefore, if further research or clinical evidenceindicates that the lower or upper limits of acceptable heart beat rateshould be altered, this may be readily accomplished.

As hereinbefore indicated, the Q output of flip-flop 5-C is connectedvia lead to the pacer while the not- Q output of flip-flop 5-C togetherwith the Q output of flip-flop 5-F are connected to gate 5-l-l foroperating normal heart indicator 5-J. The'latter suitably comprises atransistor Q50! operated by gate 5-H having a lamp in its collectorlead.

The not-Q output of J-K flip-flop 5-F is connected to one input ofriand-gate 56 of gate 5-K. The other input of nand-gate 56 is derivedfrom nand-gate 54, the input of which is connected to a differentiatingnetwork comprising C503 and R509 receiving an output of flip-flop 5-E.If, in a given 8-second clock period, 25 or more input pulses arereceived at the not-Q output of J-K flip-flop 5-F will be high duringthe next clock period. if, at any time during the following clockperiod, 25 input pulses are received at an input will also be providedat nand-gate 54. Thus, if both inputs of nand-gate 56 are high for ashort interval during two consecutive clock periods of 8 seconds, aheart rate of 187.5 or greater is indicated. In turn, the output ofnand-gate 56 is applied to nand-gate 58 which provides output foroperating the defibrillator. As hereinbefore mentioned, signals on leadsand reset the first and second counters 5-A and 5-D, as well as flipp5-B and 5-E, respectively. A clear pulse on lead Considering thewaveform chart of FIG. 9, it is observed that an output occurs fromcounter 5-A for each five input pulses at The first output from counter5-A sets flip-flop 543 so that the output thereof changes from a firststate to a second state and stays in this contidition until reception ofa subsequent reset pulse. When a clock pulse is then received, the J-Kflip-flop S-C is changed from a first state to a second state, while thecounter -A and flip-flop 5-B reset via the reset pulses received at andIn the present example, second counter 5-D is operated at the end of thefourth pulse from counter S-A. At the conclusion of the fourth pulsefrom second counter S-D, flip-flop 5-E is set, and J-K flip-flop 5Fchanges state when the subsequent clock pulse is received. Thesewaveforms, of course, are only typical, and do not necessarily indicatethe exact number of input pulses which may be received between a givenpair of clock pulses for every patient. Rather, a high number of pulsesare indicated which would result in defibrillator operation.

Clock Referring to FIG. 10, gate portions 6-A' and 6-C perform thefunctions of or-gates 6-A and 6-C on the block diagram. This structureis conveniently provided as a four-nand-gate integrated circuitincluding nandgates 60, 62, 64, and 66, which are consecutivelyconnected. Nand-gate 60 receives inputs from the interface circuit, andfrom the defibrillator circuit. Providing both these inputs are up, theoutput of nandgate 60 is low, and the clock pulse generator 6-B caoperate in a normal fashion.

ln clock pulse generator 6-B, transistor 0601 receives the output ofnand-gate 60 at its base, and its collector-emitter terminals arecoupled across capacitor C601 coupled between the emitter and lower baseterminals of unijunction transistor 0602. The circuit normally operatesas a relaxation oscillator whereby the unijunction transistorperiodically discharges capacitor C601 to su ply a ulse output at itslower base. If either input or qgshould drop, transistor 0601 would berendered conducting causing C601 to discharge rapidly through R603,which serves to limit the maximum current in 0601 during dischar e ofC601. At the conclusion of such input ator the operation of theoscillator including unijunction transistor 0602 would be restarted.

The normal period of the oscillator is here adjusted to be eight secondsby means of potentiometer R606, and at the end of conduction oftransistor 0601, a new 8-second interval is started. Thus, at theconclusion of a defibrillator pulse, or the conclusion of a period oftime during starting, or a period of time when the electrodes areimproperly connected to the patient, a new 8- second interval willstart.

The output of unijunction transistor 0602 is connected via a Schmitttrigger circuit, comprising transistors 0603, 0604, and 0605, to aninput of nandgate 68, the output of which provides the clock pulse onlead The output of the Schmitt trigger circuit comprising transistors0603, 0604, and 0605 is also coupled to a second Schmitt trigger circuitcomprising transistors 0606 and 0607. The output of the latter triggercircuit is applied to nand-gate 70 and the output of nand-gate 70 isconnected to an input of nand-gate 74 which forms flip-flop 6-D togetherwith nand-gate 72. The output of nand-gate 74 is connected to one inputof nand-gate 72, and vice versa. Another input of nand-gate 72 isderived from the output of nand-gate 62. As thus appears, flip-flop 6-Dwill be set upon the operation of hand-gates 60 and 62, and will then bereset upon the occurrence of a clock pulse. The signal at from nand-gate74 enables the pacemaker at the first clock pulse after power has beenapplied for a short period, or after any difiiculty with respect tocontinuity has been rectified, or after the occurrence of adefibrillator pulse. Thus, as hereinbefore mentioned, the pacer isdisabled until a proper count can be made.

The output of nand-gate drops at the end of a clock pulse, and theoutput of nand-gate 70 is also applied to nand-gate 64 in conjunctionwith the output of hand-gate 62. Thus, assuming both signals and are up,a reset is provided by nand-gate 64 on leadat the conclusion of a clockpulse. This signal is inverted by hand-gate 66 to provide the resetsignal on lead@.

It is noted a clear signal is provided on lead 20 at the same time thateither input or lowers, and the JK flip-flops in the counter circuitwill be cleared at such time.

Pacer In FIG. 11, nand-gate 7-A receives inputfrom the counter, andenabling signal from the clock circuit, and reset signal from thecomparator. Input from the counter is the one indicating a slow heartbeat and desirability for applying pacing pulses. Enabling signalindicates that the interface is operating properly and that sufiicienttime has elapsed for the counter to make a proper count afterapplication of power or application of a defibrillator pulse. The outputof gate 7-A, which here comprises a nand-gate, is applied to transistor0702, and assuming all three of the aforementioned inputs, and arepresent, the input to transistor 702 will be low. Therefore, the pacer7-B is operable.

Pacer timer 7-B comprises a unijunction transistor 0703 having acapacitor C703 coupled between its emitter terminal and lower base. Thiscircuit is a relaxation oscillator similar to that described inconnection with the clock circuit, except in the present instance therelaxation oscillator suitably has a period of approximately 0.85seconds. The output of timer 7-B is applied to one-shot multivibrator7-C including transistors 0704 and 0705. The output at the collector oftransistor 0705 is a series of positive pulses, each pulse having aduration of about milliseconds, and this output is connected to theinput of nand-gate 76. Nand-gate 76 provides signal applied to thesignal conditioning circuit for disabling the signal channel when apacer pulse is being generated. It should be noted that the duration ofthe output pulse at is considerably longer than the duration of thepacing pulse applied to the patient. This allows time for the amplifier11-3 and signal conditioning circuit 2-A to recover from the overdrivencondition imposed by the pacing pulse.

The output of one-shot multivibrator circuit 7-C is also applied viatransistor 0706 as the input of pulse transformer T701, the secondary ofwhich is coupled to provide the input of thyristor 0701. AC voltage froma power supply is normally applied across a bridge circuit comprisingdiodes D701, D702, D703, and D704 connected in DC charging relationshipto capacitors C701 and C702, with thyrister 0701 being interposedbetween the positive end of capacitor C702 and connectiorcoupled to thepatient electrodes. Thus when transistor Q706 turns on, current flowrapidly increases through the primary winding of pulse transformer T701,and a resultant secondarypulse triggers thyristor Q701 into a conductingstate. When thyristor 0701 is turned on, capacitor C702 dischargesthrough diodes l-F and through the patients body. As capacitor C702discharges, the current through thyristor Q70l decreases until theminimum holding current is reached. At this point, thyristor Q70l turnsoff, and capacitor C702 begins recharging.

If, during the operation of the pacer, spontaneous heart beats occur inthe patient, the spontaneous beats are detected by the comparatorcircuit, and a low level pulse is applied to one input of gate7A.resetting the pacer timer. Another pacing pulse will occur after 0.85seconds unless another spontaneous beat takes place. Thus, the pacer isof the demand type and produces pacing pulses only in the absence ofspontaneous heart beats in the patient.

- Defibrillator Referring to FIG. 12, illustrating the-defibrillator 8,an input is received at from counter 5 when a count for two consecutivec ock periods reveals an unacceptably high input pulse rate indicativeof ventricular fibrillation or ventricular tachycardia. The input pulseoperates one-shot multivibrator 8-A, comprising transistors 0802 and0803, which in turn applies a lengthened output to gate 8-B, herecomprising nandgate 78, 79, and 80 consecutively connected. The outputof nand-gate 78 is connected to leads which respectively disable andrecycle the clamp the input signal channel during the defibrillatorpulse. The output of the one-shot multivibrator 8-A is longer than theduration of the defibrillating pulse applied to the patient to allowtime for the amplifier and signal conditioning circuits to recover.Signal@, comprising a disabling input from the interface circuit, isalso connected to nand-gate 80, and when this signal drops, indicatingimproper connection of the patient electrodes or the start of operation,the defibrillator is disabled.

The output of nand-gate 80 is connected to the base of transistor 0801which has the operating coil of relay K801 serially connected in itscollector circuit. The contacts of relay K801 normally connect capacitorC801 to the output of a bridge circuit comprising diodes D801, D802,D803, and D804, receiving a high voltage alternating current input.However, when transistor 0801 conducts, relay K801 connects capacitorC801, theretofore charged through the aforementioned bridge circuit, toleads@and@via inductance L801. Lead(@an@are coupled through diodes l-Eto the patient electrodes, as hereinbefore mentioned. Capacitor C801,initially charged to a high voltage from the power supply, applies thishigh voltage across a circuit comprising inductance L801, the switchingdiodes l-E, and the body resistance of the patient. [n-

16 lowed to pass through the disabling clamp 2-B so that monitoring ofthe electrocardiac signal is resumed.

Operation In general operation, the device is applied to the suspectedheart attack patient as illustrated in FIG. 1, with the patientelectrodes in direct contact with his body. Thus, patient electrodeispositioned in good contact with the patients chest, and patientelectrode@ is positioned in direct-contact with the patients back,forward and rearward of the heart, respectively. The device is turned onto operate the apparatus power supplies, and if proper contact is notmade with the patient, indicator 1-D will light, and moreover, operationof the instrument is prevented. Normally, counter 5 will cycle under thecontrol of clock 6 for the first eightsecond period, and if a normalheart rate is counted, normal heart indicator 5-] will light. However,if a cardiac arrest has taken place, or the heart rate is extremely low,pacer 7 will operate through switching diodes l-F, and the patientelectrodes, to provide a pacing pulse to the patient as long asrequired. Should a normal heart beat resume without the aid of thepacer, the pacer will be disabled via inputof and-gate 7-A. lf,

- on the other hand, the heart rate is excessively high, in-

ductance L801 controls the resulting current. At the 6 conclusion of thedefibrillation pulse, clock 6 is recycled as the output at rises. Thus,the clock circuit begins a new eight second period, and signals arealfirst aid personnel have reached the patient, thechances for survivalare materially increased as compared with the chances for survival aftertransport of a heart patient to a hospital before possible treatment.

While I have shown and described a preferred embodiment of my invention,it will be apparent to those skilled in the art that many changes andmodifications may be made without departing from my invention in itsbroader aspects. 1 therefore intend the appended claims to cover allsuch changes and modifications as fall within the true spirit and scopeof my invention.

l claim: 1. A cardiac resuscitator comprising: electrode means forapplication to a patient suffering from possible heart attack, meanscoupled to said electrode means for detecting the electrocardiac signalgenerated by the patients heart including the QRS wave of theelectrocardiac complex for indicating the patients heart beat, meansresponsive to the detecting means for determining the patients heartrate and for producing a first output for a heart rate belowpredetermined normal limits, and a second output for a heart rate abovesaid predetermined normal limits, pacer means coupled to said electrodemeans and automatically responsive to said first output for applying aperiodic pacing pulse at a predetermined rate in the range of a normalheart rate to said electrode means,

and defibrillator means coupled to said electrode means andautomatically responsive to a said second output for applying only asingle substantially higher voltage defibrillating pulse to saidelectrode means within a period on the order of at least several secondsand in response to a given determination of heart rate above saidpredetermined normal limits.

2. The apparatus according to claim 1 wherein said means responsive tosaid detecting means includes means operative for initiating said secondoutput only in response to occurrence of a heart rate above saidpredetermined normal limits for at least two successive periods ofseveral seconds each.

3. The apparatus according to claim 1 including diode means fordecoupling said detecting means from said electrode means during anoutput from said pacer means or said defibrillator means in response toan electrical output therefrom.

4. The apparatus according to claim 1 wherein said detecting meansincludes a variable sensitivity signal channel and means for storingprevious peak values detected, the sensitivity of said signal channelbeing responsive to the previous level of said peak values as stored bysaid storing means for causing said detecting means to be responsive tosignals exceeding at least a predetermined proportion of stored peakvalues.

5. The apparatus according to claim 4 further including means forlimiting the level stored by said storing means to a predeterminedmultiple of said peak values stored theretofore, a said predeterminedproportion of said multiple being less than unity.

6. The apparatus according to claim 1 including switching diode meansbetween said defibrillator means and said patient electrode means aswell as between said pacer means and said electrode means forsubstantually automatically disconnecting said pacer means and saiddefibrillator means from said electrode means and from each other exceptduring operation of one of the respective pacer means or defibrillatormeans, at which time said one of said respective pacer or defibrillatormeans is connected to said electrode means.

7. The apparatus according to claim 1 further provided with a normalheart indicator, said means responsive to the detecting means providinga third output for operating said normal heart indicator when said heartrate is within said predetermined normal limits.

8. A cardiac resuscitator comprising:

electrode means for application to a patient suffering from possibleheart attack,

means coupled to said electrode means for detecting the electrocardiacsignal generated by the patients heart including the QRS wave of theelectrocardiac complex for indicating the patients heart beat,

means responsive to the detecting means for determining the patientsheart rate and for producing a first output for a heart rate belowpredetermined normal limits, and a second output for a heart rate abovesaid predetermined normal limits,

pacer means coupled to said electrode means and automatically responsiveto said first output for applying a periodic pacing pulse at apredetermined rate to said electrode means,

U-shaped applicator, said U-shaped applicator being positionable foryieldably urging said electrode means into firm contact with thepatients body, one of said electrode means being mounted from an upperleg of said applicator for location against the patients chest over theheart area, and a second separately connected electrode means beingmounted upon a lower leg of said applicator for positioning against thepatients back opposite the first mentioned electrode means. 9. Theapparatus according to claim 8 wherein said applicator further carriesan indifferent electrode for application to the patients body at aseparate location, and means for connecting the indifierent electrode toa neutral or grounded point in the apparatus. 10. A cardiac resuscitatoecomprising: electrode means for attachment to a patient suffering frompossible heart attack,

means coupled to said electrode means for detecting an electrocardiacsignal generated by the patents heart including successive pulsesderived from the electrocardiac complex for indicating the patientsheart beat,

means responsive to the detecting means for counting said successivepulses during a predetermined period of time for producing a firstoutput for a heart rate below predetermined normal limits, and a secondoutput for a heart rate above said predetermined normal limits,

pacer means coupled to said electrode means and responsive to said firstoutput of said counting means for applying a periodic pacing pulse at apredetermined rate in the range of a normal heart rate to said electrodemeans,

and defibrillator means coupled to said electrode means and responsiveto a said second output of said counting means for applying only onesubstantially higher voltage defibrillating pulse to said electrodemeans within a period on the order of at least several seconds.

11. The apparatus according to claim 10 further including a clock meansoperatively connected to said counting means for predetermining a periodof time during which said counting means counts said pulses, whereinsaid clock means resets and recycles said counting means.

12. The apparatus according to claim 11 including means for determiningthe continuity between said electrode means and the patients body, andmeans for inhibiting said clock means as well as inhibiting said pacermeans and defibrillator means in response to the lack of suchcontinuity.

13. The apparatus according to claim 11 wherein said counting meansincludes means for remembering a given count during a given cycle ofsaid clock means, and output means responsive to said means forremembering for producing said first and second outputs at the end of agiven cycle of said clock means.

14. The apparatus according to claim 13 wherein said defibrillator meansis provided with connection means coupled for resetting said clock meansand said counting means, and connection means for clearing said meansfor remembering, upon the occurrence of a defibrillating pulse.

15. The apparatus according to claim including means for inhibitingoperation of said pacer means until time has elapsed for occurrence ofan output from said counting means.

16. The apparatus according to claim 10 wherein said counting meanscomprises:

a first counter operable to produce an output after a predeterminednumber of said pulses,

first storing means for temporarily storing'an output of said firstcounter,

a second counter responsive to the output of the first counter,

and a second storing means for temporarily storing an outputof thesecond counter,

a first output means for receiving and remembering an output fromsaidfirst storing means indicative of a heart rate below a predeterminedminimum rate,

and a second output means for receiving and remembering an output fromsaid second storing means indicative of a heart rate above apredetermined maximum rate.

17. The apparatus according to claim 16 wherein said first output isprovided by said first output means, and further including means forrecycling said first and second countersand for recycling said first andsecond storage means, and gate means providing said second output inresponse to a level of said second output means and said second storingmeans at a given time to produce said second output after two successivecounting cycles for indicating a heart rate a above said predeterminednormal limits.

18. A cardiac resuscitator comprising:

electrode means for attachment to a patient suffering from possibleheart attack,

means coupled to said electrode means for detecting an electrocardiacsignal generated by the patients heart including successive pulsesderived from the electrocardiac complex for indicating the patientsheart beat,

means responsive to the detecting means for counting said successivepulses during a predetermined period of time for producing a firstoutput for a heart rate below predetermined normal limits, and a secondoutput for a heart rate above said predetermined normal limits, saidcounting means comprising a first counter operable to produce anindication after a predetermined number of pulses and a second counterfor producing a second indication after a higher count of pulses, saidfirst output being responsive to the indication of said first counter,and said second output being responsive to said second indication,

pacer means coupled to said electrode means and responsive to said firstoutput of said counting means for applying a periodic pacing pulse at apredetermined rate to said electrode means,

and defibrillator means coupled to said electrode means and responsiveto said second output of said counting means for applying adefibrillating pulse to said electrode means.

19. The apparatus according to claim 18 wherein said second counterreceives as its input the said indication of said first counter. v

20. The apparatus according to claim l8including means responsive tosaid indication of said first counter and the absence of an indicationfrom said second counter for producing a third output indicative of aheart rate within said predetermined normal limits.

21. The apparatus according to claim 1 wherein said detectingmeansincludes means for detecting positive excursions of saidelectrocardiac signal, means for detecting negative excursions of saidelectrocardiac signal, means for determining the predominant polarity ofsaid electrocardiac signal, and gating means responsive to the lastmentioned means for coupling an output from the detecting means thepolarity of which predominates.

22. A cardiac resuscitator comprising:

electrode means for application to a patient suffering from possibleheart attack,

means coupled to said electrode means for detecting the electrocardiacsignal generated by the patients heart including the QRS wave of theelectrocardiac complex for indicating the patients heart beat,

means responsive to the detecting means for determining the patientsheart rate and for producing a first output for a heart rate belowpredetermined normal limits, and a second output for a heart rate abovesaid predetermined normal limits,

pacer means coupled to said electrode means and automatically responsiveto said first output for applying a periodic pacing pulse at apredetermined rate to said electrode means,

defibrillator means coupled to said electrode means and automaticallyresponsive to said second output for applying a higher voltagedefibrillating pulse to said electrode means,

means for determining the continuity of connection of said electrodemeans with a patients body, said means for determining the continuityincluding means for applying a DC current to ones of said electrodes andmeans for measuring a resulting DC voltage at the same electrodes, andmeans for inhibiting operation of said resuscitator apparatus inresponse to a lack of such continuity.

1. A cardiac resuscitator comprising: electrode means for application toa patient suffering from possible heart attack, means coupled to saidelectrode means for detecting the electrocardiac signal generated by thepatient''s heart including the QRS wave of the electrocardiac complexfor indicating the patient''s heart beat, means responsive to thedetecting means for determining the patient''s heart rate and forproducing a first output for a heart rate below predetermined normallimits, and a second output for a heart rate above said predeterminednormal limits, pacer means coupled to said electrode means andautomatically responsive to said first output for applying a periodicpacing pulse at a predetermined rate in the range of a normal heart rateto said electrode means, and defibrillator means coupled to saidelectrode means and automatically responsive to a said second output forapplying only a single substantially higher voltage defibrillating pulseto said electrode means within a period on the order of at least severalseconds and in response to a given determination of heart rate abovesaid predetermined normal limits.
 2. The apparatus according to claim 1wherein said means responsive to said detecting means includes meansoperative for initiating said second output only in response tooccurrence of a heart rate above said predetermined normal limits for atleast two successive periods of several seconds each.
 3. The apparatusaccording to claim 1 including diode means for decoupling said detectingmeans from said electrode means during an output from said pacer meansor said defibrillator means in response to an electrical outputtherefrom.
 4. The apparatus according to claim 1 wherein said detectingmeans includes a variable sensitivity signal channel and means forstoring previous peak values detected, the sensitivity of said signalchannel being responsive to the previous level of said peak values asstored by said storing means for causing said detecting means to beresponsive to signals exceeding at least a predetermined proportion ofstored peak values.
 5. The apparatus according to claim 4 furtherincluding means for limiting the level stored by said storing means to apredetermined multiple of said peak values stored theretofore, a saidpredetermined proportion of said multiple being less than unity.
 6. Theapparatus according to claim 1 including switching diode means betweensaid defibrillator means and said patient electrode means as well asbetween said pacer means and said electrode means for substantuallyautomatically disconnecting said pacer means and said defibrillatormeans from said electrode means and from each other except duringoperation of one of the respective pacer means or defibrillator means,at which time said one of said respective pacer or defibrillator meansis connected to said electrode means.
 7. The apparatus according toclaim 1 further provided with a normal heart indicator, said meansresponsive to the detecting means providing a third output for operatingsaid normal heart indicator when said heart rate is within saidpredetermined normal limits.
 8. A cardiac resuscitator comprising:electrode means for application to a patient suffering from possibleheart attack, means coupled to said electrode means for detecting theelectrocardiac signal generated by the patient''s heart including theQRS wave of the electrocardiac complex for indicating the patient''sheart beat, means responsive to the detecting means for determining thepatient''s heart rate and for producing a first output for a heart ratebelow predetermined normal limits, and a second output for a heart rateabove said predetermined normal limits, pacer means coupled to saidelectrode means and automaTically responsive to said first output forapplying a periodic pacing pulse at a predetermined rate to saidelectrode means, and defibrillator means coupled to said electrode meansand automatically responsive to said second output for applying a highervoltage defibrillating pulse to said electrode means, said apparatusincluding a U-shaped applicator wherein said electrode means are carriedby said U-shaped applicator, said U-shaped applicator being positionablefor yieldably urging said electrode means into firm contact with thepatient''s body, one of said electrode means being mounted from an upperleg of said applicator for location against the patient''s chest overthe heart area, and a second separately connected electrode means beingmounted upon a lower leg of said applicator for positioning against thepatient''s back opposite the first mentioned electrode means.
 9. Theapparatus according to claim 8 wherein said applicator further carriesan indifferent electrode for application to the patient''s body at aseparate location, and means for connecting the indifferent electrode toa neutral or grounded point in the apparatus.
 10. A cardiac resuscitatoecomprising: electrode means for attachment to a patient suffering frompossible heart attack, means coupled to said electrode means fordetecting an electrocardiac signal generated by the patent''s heartincluding successive pulses derived from the electrocardiac complex forindicating the patient''s heart beat, means responsive to the detectingmeans for counting said successive pulses during a predetermined periodof time for producing a first output for a heart rate belowpredetermined normal limits, and a second output for a heart rate abovesaid predetermined normal limits, pacer means coupled to said electrodemeans and responsive to said first output of said counting means forapplying a periodic pacing pulse at a predetermined rate in the range ofa normal heart rate to said electrode means, and defibrillator meanscoupled to said electrode means and responsive to a said second outputof said counting means for applying only one substantially highervoltage defibrillating pulse to said electrode means within a period onthe order of at least several seconds.
 11. The apparatus according toclaim 10 further including a clock means operatively connected to saidcounting means for predetermining a period of time during which saidcounting means counts said pulses, wherein said clock means resets andrecycles said counting means.
 12. The apparatus according to claim 11including means for determining the continuity between said electrodemeans and the patient''s body, and means for inhibiting said clock meansas well as inhibiting said pacer means and defibrillator means inresponse to the lack of such continuity.
 13. The apparatus according toclaim 11 wherein said counting means includes means for remembering agiven count during a given cycle of said clock means, and output meansresponsive to said means for remembering for producing said first andsecond outputs at the end of a given cycle of said clock means.
 14. Theapparatus according to claim 13 wherein said defibrillator means isprovided with connection means coupled for resetting said clock meansand said counting means, and connection means for clearing said meansfor remembering, upon the occurrence of a defibrillating pulse.
 15. Theapparatus according to claim 10 including means for inhibiting operationof said pacer means until time has elapsed for occurrence of an outputfrom said counting means.
 16. The apparatus according to claim 10wherein said counting means comprises: a first counter operable toproduce an output after a predetermined number of said pulses, firststoring means for temporarily storing an output of said first counter, asecond counter responsive to the output of the first counter, and asecond storing means for temporarily storing an ouTput of the secondcounter, a first output means for receiving and remembering an outputfrom said first storing means indicative of a heart rate below apredetermined minimum rate, and a second output means for receiving andremembering an output from said second storing means indicative of aheart rate above a predetermined maximum rate.
 17. The apparatusaccording to claim 16 wherein said first output is provided by saidfirst output means, and further including means for recycling said firstand second counters and for recycling said first and second storagemeans, and gate means providing said second output in response to alevel of said second output means and said second storing means at agiven time to produce said second output after two successive countingcycles for indicating a heart rate above said predetermined normallimits.
 18. A cardiac resuscitator comprising: electrode means forattachment to a patient suffering from possible heart attack, meanscoupled to said electrode means for detecting an electrocardiac signalgenerated by the patient''s heart including successive pulses derivedfrom the electrocardiac complex for indicating the patient''s heartbeat, means responsive to the detecting means for counting saidsuccessive pulses during a predetermined period of time for producing afirst output for a heart rate below predetermined normal limits, and asecond output for a heart rate above said predetermined normal limits,said counting means comprising a first counter operable to produce anindication after a predetermined number of pulses and a second counterfor producing a second indication after a higher count of pulses, saidfirst output being responsive to the indication of said first counter,and said second output being responsive to said second indication, pacermeans coupled to said electrode means and responsive to said firstoutput of said counting means for applying a periodic pacing pulse at apredetermined rate to said electrode means, and defibrillator meanscoupled to said electrode means and responsive to said second output ofsaid counting means for applying a defibrillating pulse to saidelectrode means.
 19. The apparatus according to claim 18 wherein saidsecond counter receives as its input the said indication of said firstcounter.
 20. The apparatus according to claim 18 including meansresponsive to said indication of said first counter and the absence ofan indication from said second counter for producing a third outputindicative of a heart rate within said predetermined normal limits. 21.The apparatus according to claim 1 wherein said detecting means includesmeans for detecting positive excursions of said electrocardiac signal,means for detecting negative excursions of said electrocardiac signal,means for determining the predominant polarity of said electrocardiacsignal, and gating means responsive to the last mentioned means forcoupling an output from the detecting means the polarity of whichpredominates.
 22. A cardiac resuscitator comprising: electrode means forapplication to a patient suffering from possible heart attack, meanscoupled to said electrode means for detecting the electrocardiac signalgenerated by the patient''s heart including the QRS wave of theelectrocardiac complex for indicating the patient''s heart beat, meansresponsive to the detecting means for determining the patient''s heartrate and for producing a first output for a heart rate belowpredetermined normal limits, and a second output for a heart rate abovesaid predetermined normal limits, pacer means coupled to said electrodemeans and automatically responsive to said first output for applying aperiodic pacing pulse at a predetermined rate to said electrode means,defibrillator means coupled to said electrode means and automaticallyresponsive to said second output for applying a higher voltagedefibrillating pulse to said electrode means, means for deTermining thecontinuity of connection of said electrode means with a patient''s body,said means for determining the continuity including means for applying aDC current to ones of said electrodes and means for measuring aresulting DC voltage at the same electrodes, and means for inhibitingoperation of said resuscitator apparatus in response to a lack of suchcontinuity.